Airborne-Relay-Based Algorithm For Locating Crashed Uavs In Gps-Denied Environments

We propose a location algorithm to promptly search for crashed unmanned aerial vehicles (UAVs), using an airborne communication relay UAV (ACRU) in global positioning system (GPS)-denied environments. Conventional UAV based location methods require at least four UAVs to search for the crashed one. However, such methods are subject to significant errors according to the distance between the crashed UAV and the others. In the proposed algorithm, only one ACRU is required to locate the crashed UAV. The ACRU relays its own position and the signals from the crashed UAV in real-time to a ground control station (GCS), which then estimates the position of the crashed UAV based on time difference of arrival (TDOA) processing using the signals relayed from the ACRU. According to the estimated position of the crashed UAV, the ACRU then flies in the direction of the crashed UAV by applying a weighting algorithm to effectively estimate the distance to it. The performance of the proposed algorithm is verified by computer simulations by considering the conditions of an army battalion battlefield. We improve the accuracy of the proposed location algorithm by applying a weighting algorithm to the TDOA data, and we demonstrate that the location algorithm can be used to efficiently locate crashed UAVs in GPS denied environments.